Treating tobacco

ABSTRACT

The flavor of tobacco smoke is influenced by the addition of a substance of the following formula IN WHICH R represents -CH2-CHO, -(CH2)2-CHO, -CO-CHO, -CH2-COCHO, -CH2OH, -(CH2)2OH, -OHOH-CH2-CH3, -CO-(CH2)3OH, -CO-CHOHCH3, or -CO-COO-C2H5. The added compound comprises approximately 0.001 percent to 1.0 percent by weight of the tobacco composition.

llie ttea atent Nenratlr et all.

[54] TREATHNC TOBACCO [72] Inventors: Georg Neurath, Eichtalstrasse 27; Michael C Dunger, Kienholt 6a, both of Hamburg;

Herbert Wichern, Hazenwisch 65, Ha]- stenbek, all of Germany [22] Filed: Feb. 20, 1969 [21] Appl.No.: 301,156

[52] lU.S.Cl ..1l31/1l44, 131/17 [51] Int. Cl... A24b 03/12, A24b 15/04 [58] Fieldofsearcln ..l3l/l7, 140-144 [56] References Cited FOREIGN PATENTS OR APPLICATIONS 6,703,l64 9/1967 Netherlands ..l3 l/17 OTHER PUBLICATIONS Dangerous Properties of Industrial Material- (Text) by N. Irving Sax (1968) Reinhold Book Corp. N.Y. p. 1,069 cited Dangerous Properties of Industrial Material, (Text) by N. Irving Sax (I968) Reinhold Book Corp. N.Y. p. 934 additionally cited.

Stedman, R. L., The Chemical Composition of Tobacco and Tobacco Smoke from The Chemical Reviews Vol. 68 No. 2 April 1968 pp. 176 & I77 cited Primary Examiner-Melvin D. Rein Attorney-Wilson & Fraser [57] ABSTRACT The flavor of tobacco smoke is influenced by the addition of a substance of the following formula The present invention relates to methods for influencing the flavor of tobacco smoke and a principal aim of the invention is to make it possible to produce predictable flavoring results. Although the invention is more particularly concerned with natural tobaccos, it can also be applied to synthetic or artificial tobacco foil. The invention can be applied to natural tobaccos lacking in aroma or tobaccos which are neutral in flavor. Furthennore the invention may be applied to substances to be smoked which are not of a tobacco nature, for example medicinal cigarettes or to cigarette filter materials. For the sake of convenience of terminology in the present specification and claims, and because the invention if chiefly applicable to smoking materials from the tobacco plant, all smoking and filter materials are spoken of as tobacco.

In accordance with a previous proposal as made in the German Pat. specification 1,131,580 synthetic tobacco fibers were to be produced by subjecting a chosen tobacco mixture to alternating extraction treatments to remove water-soluble and alcohol-soluble aroma materials which were then mixed in the form of a dry extract with a carrier substance of cellulose or methylcellulose material. The fibers were spun so as to produce a cigarette tobacco resembling a natural cigarette tobacco mixture.

The aim of this method wasexclusively the production of a synthetic tobacco which was free of woody and cellulosic tobacco constituents. There was no intention to bring about a systematic and predictable flavoring of a given natural tobacco or natural tobacco mixture.

A similar principle was followed in the method described in the British Pat. No. 989,703 in which tobacco rich in aroma was subjected to careful extraction, for instance with ice-cold water, the extract so obtained freeze-dried and applied to tobacco which was poor in aroma. This method can be used for extracting one or more components of a tobacco and adding it to another tobacco, both tobaccos later being used for producing a cigarette tobacco mixture. The method could be used for adding the flavor of a tobacco to a tobacco mixture without the necessity of adding the tobacco itself, that is to say only its extract would be added.

Further methods of making extracts from natural tobaccos are described in the British Pat. No. 298,151. In accordance with this prior proposal tobacco waste, which could otherwise not be used, was to be subjected to water extraction and the extract used for improving the flavor of tobaccos for smoking. It is, however, not possible to produce a predictable and systematic modification of the flavor of a natural tobacco with this method.

Such a predictable modification of tobacco flavor was, however, to be pursued in accordance with the method of the US. Pat. No. 3,174,485 which proposed that certain organic compounds should be added to avoid variations in flavor in a par ticular cigarette tobacco mixture. The method was not intended to produce new flavor qualities in a tobacco.

In accordance with further known methods certain pyrrol derivatives were to be added in small quantities to tobacco. In accordance with the British Pat. No. 1,017,710 ZacetyI-S- methylpyrrol was to be added while the U.S. Pat. No. 3,280,824 proposed the addition of 2-fonnyl-5-methylpyrrol with a cherry aroma. In accordance with the US. Pat. No. 3,334,637 l-methyl-Z-pyrroI-carboxaldehyde was to be used. On the other hand, a cherry flavor is so removed from that of natural tobacco that it does not appeal to the majority of cigarette smokers.

One object of the present invention is to provide a method which is suitable for supplementing and strengthening the flavor of tobaccos which are poor in aroma. v

A still further object of the invention is to provide a method of producing a cigarette tobacco mixture in which the efiect of expensive component tobaccos is replaced by the addition of aroma producing substances without the overall aroma of the smoke of the finished mixture being impaired.

The present invention consists in a method for influencing the smoke flavor of tobacco which comprises the addition of a compound of the following general formula Examination of the flavor of the smoke of tobacco treated in this manner has shown that a refreshing almond characteristic is imparted though some experts consider the flavor to be more like that of liquorice.

In tests carried out on the smoke of tobacco treated in accordance with the invention it was possible to show that 2,5- or 1,2-disubstituted pyrrols produce an influence which is unnatural, especially in the case of the Z-acetyl-S-methylpyrrol proposed in the British Pat. No. 1,017,710. On the other hand, the use of 2-monosubstituted pyrrols in accordance with the invention brings about a quite general strengthening or reinforcement of the flavor of tobacco smoke. Although it is often possible to detect a qualitative and not only a quantitative difference, such a qualitative difi'erence is not found to be what could be described as foreign to the natural tobacco aroma and the qualitative difierence does not dominate the natural flavor or impair it. The difference between the prior art disubstituted pyrrols and the monosubstituted pyrrols in ac cordance with the invention is substantially independent of the quantity added to the tobacco. Substituted pyrrols need only be added in small quantities, for instance as low as 0.001 percent of the weight of the tobacco, to produce an influence on the flavor of the smoke. When added in quantities of this order a compound of the type to be used in accordance with the invention, or mixtures of such compounds do not have any harmful physiological efiects on the smoker. The materials to be used in accordance with the method of the invention only develop their specific aroma in the tobacco smoke: In other words any aroma that they may have in the pure state before being mixed with the tobacco is different to that which they appear to have in the tobacco smoke.

Owing to their low vapor pressure the substances to be used in accordance with the method of the invention remain in a satisfactory concentration in tobacco products despite long periods of storage so that after such periods of storage no loss in aroma can be detected. However, it is to be noted that owing to the ease with which the substances are entrained by water vapor in tobacco being smoked, the substances are highly efl'ective in influencing the aroma of the smoke.

The monosubstituted pyrrols to be used in accordance with the invention can be used singly or mixed together and can be added to a tobacco mixture as a whole or to one component before it is added to the rest of the mixture whose flavor or aroma is to be influenced. Application can for example be by dipping the tobacco in solutions of the substituted pyrrols in suitable highly volatile solvents. Application can also be carried out by spraying on such solutions. The application can be at any suitable stage in the tobacco manufacturing process, for example in the case of cigarette production. It has been found convenient to spray on an 1-5 percent W/V ethanolic solution of the substance or substances onto cut tobacco before it is passed into a cigarette making machine. The monosubstituted pyrrols to be used in the method in accordance with the inven tion can be synthetised comparan'vely easily. 2-acylated pyrrols can for example be obtained by reaction of pyrrolmagnesium bromide with suitable esters.

(Substituted pyrrols which can be added include 2-formylpyrrol, pyrryl-2-carbinol, pyrryl-2methylketone, pyrryl-2- ethylketone, pyrryl-Py-hydroxypropylketone, l-(pyrryl-2)- propandionel ,2, l-(pyrryl-2)-propanone-l-0l-2, methyl pyrrol-2-carboxylate, and ethyl pyrryl-Z-glyoxylate.)

pyrrol with dimethylformamide and phosphorus oxychloride with a 70 percent yield (J. Org. Chem. 20, page 668 (1955)).

The reduction of 2-acylated pyrrols to the corresponding pyrrol carbinols can be carried out in an alkaline medium.

Pyrrylmagnesium bromide reacts with butyrolacetone with the formation of 2-( -hydroxypropyl)-a-pyrrylketone.

By the reaction with chlorocarbonic acid esters pyrryl-2- carboxylic acid esters are obtained (Garr.chim. ital. 42, II,

K j ClCOOR -M B COOR N g r For the synthesis of l-(pyrryl-2)-propyndione-1,2, ethyl pyruvate is reacted with ethyl orthoformate to produce the ketal and reacted with pyrrylmagnesium bromide.

OR OR The ketoketal obtained is then heated with diluted hydrochloric acid to form the dione which is selectively reduced with sodium boron hydride to form l-(pyrryl-2)-propyndione-l-01-2. All steps in the reaction chain produce good yields.

002115 OCzH5 O OH l M NaBHa N N N H H H I H 6 The following examples illustrate production of substituted pyrrols to be used in accordance with the method of the invention.

EXAMPLE I 2-formylpyrrol While stirring g. of phosphorus oxychloride was slowly added to 40 g. dimethylformamide and then, during a period of 15 minutes, ml. of dichloromethyne were added slowly with continued stirring. Following this 33.5 g. of pyrrol were dissolved in 125 ml. of dichloromethyne and the reaction mixture was heated with reflux cooling for 15 minutes. A solution of 375 g. sodium acetate in 500 ml. of water was stirred in and in the following 10 minutes the mixture was cooled to room temperature. The methylene chloride was separated from the aqueous phase, the latter extracted a few times with ether and the combined organic phases were washed until neutral with sodium hydrogen carbonate solution. The residue was dried over sodium sulfate, filtered and subjected to evaporation. It was then distilled. The yield was 69 percent.

Data regarding the compound is as follows:

8p, nor-107 c.

Mp 44'45 C. Molecular weight 95 UV... 286 nm C H N Theoretical composition: 63.20 5.25 17.75 Found: 63. lo 4.86 l7.76

In order to assess the flavor brought about by the addition of the substance to a tobacco mixture, a mixture to be used for making cigarettes of normal quality and free of any artificial flavoring substance, for example essential oils or the like, was sprayed with a 2.5 percent W/V ethanolic solution of 2-formylpyrrol, stored for a week at 20 C. and 67 percent relative humidity and then made into cigarettes. The cigarettes so produced were then tested by a panel of experts so as to make a comparison with untreated tobacco mixture as regards flavor. The quantity of solution applied to the tobacco mixture was so chosen that the cigarettes of treated tobacco contained 0.001 percent by weight (or 0.0l percent in the tobacco smoke condensate) more 2-formylpyrrol (as regards the main smoke stream) than was the case with cigarettes of the same but untreated tobacco mixture for purposes of comparison. The necessary quantity of solvent was empirically determined in preliminary tests. The smoking of the cigarettes for these preliminary tests was carried out in accordance with the VdC Standards (see Beitrage zur Tabakforschung l, page 32 (l96l 1, page 307 (1962)) in accordance with the draft DIN Standard 10.240. The panel were practically unanimous in their verdict that the cigarettes made of treated tobacco were fuller in their general flavor qualities, there being a distinct almond savor.

EXAMPLE ll pyrryl-2-carbinol A solution of 1 1 g. of sodium borohydride in 55 ml. of water was rapidly added while stirring to a solution of 10 g. 2-formylpyrrol in ml. water. After stirring for a further hour potassium carbonate was added till saturation was obtained, the aqueous phase was extracted with ether, the extract dried over sodium sulfate and the ether evaporated. The residue was then distilled under reduced pressure. The yield was 83 percent.

P/u 121 123 0. Molecular weight 95 xnm 217 nm EXAMPLE III pyrryl-Z-methylketone A solution of 1 g. ethyl bromide in 100 ml. absolute ether were added slowly while stirring to 24 g. magnesium in 200 ml. absolute ether and after 30 minutes had elapsed a solution of 76 g. pyrrol in absolute ether was added. Following this the reaction solution was held for 30 minutes at the boiling point and then cooled to room temperature After the addition of 97 g. ethyl acetate in 100 ml. absolute ether the reaction mixture was again held for 30 minutes at the boiling point and after cooling to room temperature 1 mole of 10 percent hydrochloric acid was added. The organic phase was separated from the aqueous phase, dried over sodium sulfate and the ether evaporated. The residue was distilled under reduced pressure. The yield was 73 percent.

Bp/ l05-108 c.

Mam... 89-90 c.

Molecular 109 weight UV 286 nm Theoretical composition: 66.05 6.30 12.83 Found: 66.37 6.21 13.22

As was the case with tobacco treated with the material of example l the smoke had a smooth V-mark with a generally more pronounced overall impression with a distinct almond oil flavor.

EXAMPLE IV pyrryl-Z-ethylketone Using the same procedure as described in the following example V 6.7 g. pyrrol, 12 g. ethyl bromide, 2.7 g. magnesium and 11.2 g. ethyl propionate were used to produce 8.8 g. pyrryl-2-ethylketone, the yield being 72 percent.

Mm"... 5042" c.

Molecular weight 1 Theoretical composition: 68.30 7.32 l 1.38 Found: 68.74 7.20 11.29

Cigarettes produced with tobacco flavored with pyrryl-2 ethylketone produced smoke which had a clearly more pronounced flavor than was the case with cigarettes made of untreated tobacco. There was also an almond savor.

EXAMPLE V CgHnNOa The pyrrolmagnesium bromide prepared using 6.7 g. pyrrol, 12 g ethylbromide and 2.7 g. magnesium in accordance with example [I] was added while stirring to a solution of 8.6 g. butyrolactone in 50 ml. of absolute ether. After stirring intensively for a further 2 hours a molar quantity of hydrochloric acid was added and the preparation carried out as in example Ill. The yield of pyrryl-2-y-hydroxypropylketone amounted to 41 percent.

Bp/ l25l30 C. Mp 53-55 Molecular weight 153 U V 285 not C N Theoretical composition: 62.75 9.16 7.19 Found: 62.82 9.26 7.29

The smoke flavor had a liquorice quality which was well blended with the other taste features. The smoke had the quality of freshness.

EXAMPLE Vl l-(pyrryl-2)-2,2-diethoxypropanone-1 Twenty-two g., corresponding to a yield of 64 percent, of 1- (pyrryl-2)-2,2-diethoxypropanone-1 were obtained from 1 1 g. pyrrol, 4.4 g. magnesium, 20 g. ethyl bromide and 31 g. 2,2- diethoxy-propionic acid ethylester.

Bpttui l0 1 C. M p 29'- 32 C. U Vim. 296 nm C H N Theoretical composition: 62.55 8.06 6.64 Found: 61.95 8.08 6.76

EXAMPLE Vll 1(pyrryl-2 )-propandione- 1 ,2

i CdlzNOg Twelve g. of l-(pyrryl-Z )-2,2-diethoxypropanone-l were boiled in 200 ml. of water with 0.03 ml. concentrated sulfuric acid for 30 minutes. After cooling the solution was extracted twice with ether, the extract neutralised with sodium hydrogen carbonate solution and dried over sodium sulfate. After filtration in contact with active carbon the ether was evaporated and the residue recrystallised from heptane. The yield was 6.5 g. and amounted to 83 percent.

p 5142 C. Molecular weight 137 U Aluux 296 C N Theoretical composition: 61.30 5.1 l 10.22 Found: 60.12 5.1 l 1004 As described in example I the compound was applied to tobacco. The tobacco then had a sott-mild quality with a nutty freshness. The V-mark was reinforced without jarring with the general flavor composition.

EXAMPLE Vlll l-(pyrryl-2)-propanone- 1-01-2 K J] 011 (HHBNU:

N ll Ii 0 Mp 8890 C. Molecular weight 138 UV). 290 nm C H N Theoretical composition: 60.42 6.48 10.07 Found: $9.24 6.66 9.99

As was the case with example I the smoke showed a reinforcement of the general flavor without any individual test components being emphasised.

EXAMPLE IX Methyl pyrryl-Z-carboxylate Using the procedure described in example V 7.4 methyl pyrryl-Z-carboxylate were obtained from 17 g. pyrrol, 30 g. ethyl bromide, 7 g. magnesium and 26 g. methyl chlorocarbonate.

Bp/ ll4122C. Pan-umnlenn Molecular weight lmzx 262 11111 C H N V Theoretical composition: 57.60 5.60 11.20 Found: 5728 5.46 10.66

When tested as in example I it was found to be mild and full with a deepening of the general flavor impression. There was a slight reinforcement of the V-character together with a liquorice savor.

EXAMPLE X ethyl pyrryl-Z-glyoxylate 11.2 g. (corresponding to yield of 68 percent) of ethyl pyrryl-2-glyoxylate were obtained from 6.7 g. pyrrol, 2.7 g. magnesium, 12 g. ethylbromide and 14g. diethyl oxylate in the manner described in example V.

Bp/y l03104 C. Plll-nnrwnlnurlnuau 39-40 C. UV Amax 308 nm C H N Theoretical composition: 57.50 5.39 8.39 Found: 57.60 5.26 8.42

wei t of the substances.

e method of the lnvention can be so carried out as to lead to the replacement of one or more components in a tobacco mixture containing the same tobacco smoke flavoring components.

What we claim is:

l. A method of improving the flavor of tobacco smoke which comprises adding to the tobacco a small amount of a flavorant, said flavorant consisting essentially of a compound of the following general formula in which R denotes CH CHO, --(CH --CHO, CO Cl-IO, CI-I COCHO, CH,OI-I, (CH,),OH, OHOH-- CH -Cl-I CO(CH -,OH, -COCHOHCl-l CO-COOC H said compound comprising approximately 0.001 percent to 1.0 percent of the weight of the tobacco composition and being without any harmful physiological effect on the smoker of the tobacco composition.

2. A method in accordance with claim 1 in which pyrryl-2- carbinol is used.

3. A method in accordance with claim 1 in which pyrryl-2- hydroxypropylketone is used.

4. A method in accordance with claim 1 in which l-(pyrryl- 2)-propanonel -ol-2 is used.

5. A method in accordance with claim 1 in which ethyl pyrryl-2-glyoxylate is used.

6. A method in accordance with claim 1 in which the compound is added in a total quantity equal to 0.01 to 0.1 percent of the weight of the tobacco. 

2. A method in accordance with claim 1 in which pyrryl-2-carbinol is used.
 3. A method in accordance with claim 1 in which pyrryl-2- -hydroxypropylketone is used.
 4. A method in accordance with claim 1 in which 1-(pyrryl-2)-propanone-1-ol-2 is used.
 5. A method in accordance with claim 1 in which ethyl pyrryl-2-glyoxylate is used.
 6. A method in accordance with claim 1 in which the compound is added in a total quantity equal to 0.01 to 0.1 percent of the weight of the tobacco. 